The present invention relates to electric power transmissions and can be used for connecting the electric power systems as well as for supplying the electric power to consumers.
At present the problem of transmitting the constantly increasing amounts of power is solved by raising the operating voltage and by erecting additional transmission lines. However, the operating voltage has a natural limit whereas the air gap used as insulator loses its insulating roperties, making further increase of the voltage impossible. In addition the electric fields of high voltage exert a negative effect upon the environment. The erection of additional lines requires new ground areas for the transmission lines, thus complicating the problem.
This problem is solved to some extent by erecting double circuit electric power transmissions, thus laying two lines on a single pole.
However, in the known double-circuit electric power transmissions the reciprocal effect of the lines upon each other increases partial inductances and reduces partial capacitances of the conductors, thus raising characteristic impedance and decreasing the transmissive capacity of each phase. The partial capacitance is enhanced to some extent by splitting each phase to a number of conductors located in a circle. However, the known design of the phase does not use other possibilities to additionally increase the partial capacitance of the conductors, exerting a substantial effect upon the increase of the total transmissive capacity of the electric power transmission.
Also known in the art are electric power transmissions by insulated cables. The feature of the cable lines consists of a great value of the charging power which depends upon the length of the cable line. The range of the electric power transmission by cable lines is limited by a distance at which the charging current becomes equal to the maximum permissible heating current of the cable.
The flow of active power in electric current transmission lines can be varied within a wide range in the intensity as well as reverse its direction. As a result some counter-currents of reactive powers of one or the other sign appear in the line, exerting an effect upon the distribution of the voltage along the line and requiring a compensation.
At present electric power systems have faults due to breaking some phases, shortcircuiting the phases to each other or to ground and the like. Hence an asymmetry of voltages appears exerting a negative effect upon the operation of multiphase systems.
When the active power to be transmitted is reduced suddenly the rotors of the generators swing, voltage fluctuations appear, thus disturbing synchronization and stability of the systems to be connected.
It is an object of the present invention to increase transmissive capacity of electric power transmission and range of its control and, reduce the intensity of the electric field in the environment of the transmission lines.
It is another object of the present invention to provide a design of the splitted phase, thus permitting to increase the mutual capacitance of conductors.
It is a further object of the present invention to provide a novel method for controlling the transmissive capacity of electric power transmission as well as to reduce the asymmetry of voltages at one of the terminals when another terminal is damaged and to enhance the operation stability of the electric power systems to be connected.
It is still another object of the present invention to increase the critical length of the cable lines.